Duct rodding machine



C. JASPER EI'AL Aug. 8, 1950v DUCT RODDING MACHINE 'Sheet's-Sheet 1Fiiea Nov. 20.1847

Aug. 8, 1950 c. JAsPR ETAL DUCT RODDING MACHINE 3 Sheets-Sheet 2 FiledNov. 20, l9 47 C. JASPER ETAL DUCT RODDING MACHINE Aug. 8, 1950 FiledNov. 20. 1u94'7 3 Sheets-Sheet 3 Patented Aug. 8, 1950 PATENT OFFICE)for-enie Jasne'r, villa .Pal-k, and George :Ti-:Hawk

Appiieauonnovemte; 20, 19117; .serial No. 787,252

This v0invention relate's, `'gene'rai'ly; to a 'self-'V contained motor'driven, 'duet rodding maoh'line. The invent'ion has particularrelationV to such a machine wherein 'the motor unit' is preferabiy' of;'the pneumatic type, 'and 'wherein .there are front' and re'ar duetlgripping units one `of which is` distendedl (in dIIct 'grippin'g'relationshi'p While the 'other is' being *advanced 'through a conduit'or duet and thereafter the second 'duct grippin'g unit is distended intoduet grippin'g relationship while i the first duet gripping unit isbeing advanced;

Although we are 'aware 'that various types of' seli-'containedV Amotordriven,v duet 'rodding mechani'sm's 'have been .previou's'ly 'suggest'ednio such mechanism has come to 'our attention 'which i nas :been capableof' pract'i'cal .and satisfactor operation for duet rodding purposes.The object of our in'vention., gener'ally stated,V is .the iprovi'sion,of a self-contained, .motor dr'veh; duet rodding lmachine capableofrapidly rodding the long lengths of ducts in common use todayand moreparticularly, uthe long underground condui'ts utilized for housingelectrical. cablesahd conductors.

An :important object 'of the. invention the prov-ision of'aselfecontained, motor driv'en, duet rodding machine capable. of rapidlyadvancing through long' ducts bymeans of a positivegripp.

ping ac'tionof theduct. or conduit withoutinju'ry thereto, and in suchajmanner. as to resistwith-= out slippage thelarge backwarl pullrequired when the machine reaches the remote endsf` of. long ducts. i vi' f nfiimportant object of the -invention is the proyision of aself-contained, motor driven, duet rt'iiiding` mechanism having' frontand rear duet.

grippin'g units which are articulated with respect:

to theintermediate motor unit thereby allowing the'mechanism tonegotiate curves or bends in a duct and pass over small offsets, ortheocolleoti'onsof foreignmaterial which oftenaccumulate in undergroundconduits. 1 yStill another 'important objectlof the inventionis 'theprovision of a self-contained, motordriven, ductfrodding machine havingapneumatic.,jtype of motor unit interposed betweenfrontandirearcontractable duct gripping units and'operable tod'iste'nd first one ofvthe-duct grippng; units intonuct Sgripping relationship.

while the otherin its. cntracted condition is advanced through the duet;and thereafter to positively zdistend the latter duet gripping unitWhlethe fOrmer, its contracted condition-, is advanced through theconduitf.

Certain other objects of the invention will, in

operation in a duet or conduit. 1

`commonly'utilized as a 'For' a more 'complete understanding `of thenature and scope of the invention, reference'inay be' had 'to thefollowing detailed description tlrereof taken in connection with theaccompanyingdrawings wherein:

Figu-re 1 isa 'side elievational view ofl av 'duet rodding machineconstitu'ting a preferred em'- b'odi-ment of the invention and shownlocated in a duet 'or conduit in one of its operative conditions;"` I IFigure 2 is a sectional View taken on line 2-'2 o'f Figure 1;

Figure 3 is a sectionai view taken on line 3=--`-3 of Ilffi'gu're 1; w

'Figura 4' is a sectionalview, partly broken away; taken 'on line fii-dof Figure 1';

Fi'gu're 5 is a sectional View'taken on line 5-5 of Figure 1; Figure 6isV 'a fragmentary, side elevati'onall View, 'partly broken away, takenadjacent line 5-5' of 'Figure l;

Figure's '7a and *7b together constitute a longitucinal sectional Viewtaken through Figure I; an' w Figures 8a andpb are l'ongitudinalsectional viewscorresponding to Fi'gures 7a and '7b but showing tl'iefArodding' machine of Figure 1 in its alternate condition ofi operation.

' Referring now 'particularl to Figure 1 of the drawings; asel'fe'contained, pneumatic motor operated Vduet 'rodd'ing me'chanism 4i is p indicated generally at In in one 'of its 'alternat'e stages of IThe duet n is illustratire 'of underground conduits and ducts housingfor cables or conductors; i

'I'he du'ct. rodding mechanism I'U compri's'es a' nectedflin articulatedrelationship with respect to the motor unit M, thereby allowing thelongitudinal. axes of the duct gripping units IZ and '13' toshift'independently of each other and of the vlongitu'dinali'axis of themotor unit. M; i 'Iihis arrangementallows the duct roddingmechan'ism F9to negotiatevor pass around bends and, to. pass oyer obstacles vin aconduit such as small offsets therein and deposits of foreign materialssuch. asy sand andimud, which ma3.T collect when the conduitisAdisposecl underground.,

The duct rodding mechanism IO is supplied with compressed air from ahose connected with the rear portion of the pneumatic motor 14. Althoughcompressed air is the preferred and usual source of fluid pressureutilized in Operating our duet rodding mechanism, it will be understoodthat other compressed gases, such as nitrogen and carbon dioxide, orfiuids under pressure such as water or oil, may be utilized whenrequired. f

In brief, the overall operation of the duet rodding mechanism 16 is asfollows:

The compressed air is admitted to the motor unit 14 through the hose 15and, depending Vupon the condition of the control valve of the motorunit, one of the duet gripping units, 12 or- 13 is caused to bedistended into duet gripping relationship. As shown in Figure 1, therear duet gripping unit 13 is so distended while the front duet grippingunit 12 is shown as eontracted. In

this condition of operation, the motor unit 14 ;f

This cycle of operation israpidly repeated causing the duet roddingmechanism 10 to advance through the duet 11 in a crawling type offorward movement.

The front and rear gripping units. V12 and 13, respectively, are ofsimilar construction but dilfer somewhat with respect to design detailsbecause of their difference lin location on the duct rodding mechanism10. ,Referring to Figures 1, 3, 7b and 8b, it will be noted that thefront duet gripping unit 12 has a central hub member26. having a pointednose 21 and three pairs'of parallel ribs 22 (Figure 3) projectingintegrally and radially therefrom, with each pair of ribs beingequi-spaced from the other two pairs by angles of 120. x

Each of the pairs of parallel ribs 22 carriesa retractable duet grippingshoe 23 of rectangular projection and arcuate cross-section for grippinga relatively large surface area of the interior of. a conduit or duet.The duct engaging surfacesV of the shoes 23 are preferably crossscoredin the manner shown in order to provide a large number of points forgreater egripping engage'ment with the interior of the conduit.

Eachshoe 23'is retractably supported inone of the pairs of-,ribs 22 by apair of links -24.and- 25. Each of the links 24 and 25 is pivotallyconnected at its outer end to the front and rearjportions, respectively,of the. shoes 23. The connections are made by means of pins 26`extending through the aligned holes in pairs of integral lugs 2`1`pro'-vided on the inner surface of each of the shoes 23 and holes provided inthe outer end of each of the links 24 and 26.

In the front duet gripping unit 12, the inner ends of the links 24 and25 are pivoted to the front and rear portions, respectively, of the hubmember by means ofpins ,28, as shown.

It will be'seen that the foregoing supporting arrangement for the threeshoes 23 perrnits them to be either contracted as shown in Figures3 and7b, or distended into duet gripping relationship as shown in Figure 8b.In order to effect the distension and contraetion Vof the shoes 23 eachof the links is by means of a pin 3 1 pivotf' front duet gripping unit12.

4 ally connected intermediate its ends with a connecting rod 30extending from the motor unit 14. Thus, each of the links 25 eonstitutesa third class type of lever fulerumed about a pin 28.

For a detailed description of the design and construction of the rearconduit gripping unit 13 reference may be had to Figures l, 2, 7a and8a. The duet gripping unit 13 has a central hub member132. having threepairs of parallel ribs 33 extending integrally and radially therefromand spaeed 120 apart with respect to each other as shown in Figure 2.Each of the pairs of parallel ribs 33 carries a duet gripping shoe 34which may eorrespond to the duet gripping shoes 23 of the Likewise, eachof the shoes 34 is supported from the central hub 32 by means of a pairof links 35 and 36. Each 'of the links 35 and 36 is pivotally connectedto the inner side of the respective shoes 34 by means of a pin 3'1extending through the outer ends of the links 35 and 36 and the pairs ofintegral lugs 38v provided on the inner sides of the shoes 34.

Each of the links 35 and 36 is pivotally connected to therespective'pairs of parallel ribs 33 adjacent the outer`edges thereof bymeans of pins 40 extending through opposite sides of the ribs 33 and thelinks 35 and 36 disposed therebetween. Each of the links 36-is in theform of a bell crank lever having an arm portion extending beyond itsrespective pin 41] with the end of'this arm portion pivotally connectedby means of a pin 42 to one of three connecting rods' 41 extending fromthe motor unit 14. It will be seen that the links 36 serve as bellcranklevers for distending and retracting the ductlgripping shoes 34,with these links being actuated by the connecting rods 41.

"',The central rub member 13 is supported from the motor unit 14 bymeans of three equi-spaced tie rods 43 extending from the motor unit 14.The outer ends of these tie rods 43 connect with the central hub 13 bymeans of ball and socket joints as shown, with balls v44. being providedon the ends of the tie rods 43, and the sockets being formed in thecentral'hub v13, as shown.

The central hub 13 is provided with'a co-axial hole 45 through thecenter thereof which serves asa conduit for transmitting air pressurefrom the air hose 15 connected to. the rear portion of the hub 32 bymeans of tan, adapter 46 to a fiexible hose section 4'1 interconnectingthe central hub 13 with the motor'unit 14. An adapter 50' connects thehose length 41 with. the front side o'fhub member 13.'

,JThe motor unit 14.has a master cylinder unit indicated generally at 51(Figure 8b) which includes a pressure cylinder 52 and a double-actingpiston 53 disposed therein; The front wall of the cylinder 52 is formedby a plug 54, while the rear wall is formed by a plug 55, the latterhaving a central opening therein,1 for accommodating a piston red 56which, is .connected at one end to the double-acting piSQLL and whichprojects from the cylinder 52 uatitsjopposite end.

' It will be noted thatjthe front plug 54 is inwardly set from the frontjend of the cylinder 52 thereby providing a short cylinder 5'1 in whichis dislzyosedv an auxiliarypiston58. The cylinder 5'1 provided by theend extension of the cylinder 52 and the piston 58 together form acombination piston, and cylinder unit whichl serves to operate the frontduet gripping unit 12.

The outer end ofV the cylinder 5'1 is closed by an end plug 66 havingthree equally'spaeed openings provided therein for jV receiving thethree equispaced projection 6,1 Vvvul'iiclfi extendv from the pis ton5.3;.. loompression; sprinzifii'. surroimdseach of. the-proiections;(ilindcacle` org-the.: endxpiugzlix and] these springSt-G'Zfnormallbios-z, the; pistom 5.8 t= a.1 nearzward on: retraeted' position:so:- thatl the pistong; ,8::l'.ir1gthroughithe` connecting:r rod's' 36normallwholds; the.- shoes- 23 of; theJ front. duet gripping, unit.v IZ;in their.-- contractedz position-as hownlinj Figureflb. ,i o A1, tierod; 6m extends from-1. az, center-i` boss.. 642.201. the Vplug- 63:'to. thev center ot: the, central-f. hub memben' Z .fofzmthez duet,|gripping; unitf 1.2.., -The ends of the tie red 63 areprovidedzwithiballs'u which: fit ;int socketsf provided. therefor7 ina.the pstonihub'ft and hubxmemben 20;. asf-'sshow-n;

ballfzand's-sockeo type offfconnection permits thefront-fductigrippingfunit. l 2-1:taxi-Shifti independ-` entiyr' offithev motor unit M12 and' yet? be' rig-idlyconnected therewithi insofaras frontrear move'- ment is concerned; 'Dhe-tie-rodsand-BT-fact as..ram-us rods permittingf: iiifnitedi` free lateral movementi. of: thehe'acis in any directionrelative to-the main motor,but?maintainingithejavi/*carrying heads i`3 and Z-at predetermineddistances frontu thefcorres-pondingmainmotor`vy parts towhichtheyare-connectedi Ini-crder that'- press-ure' may' besimultanecusly applied' to v-anolreleased? from`` the' rear of; thedouble-acting-piston 531and=the rear of' the 'auxili iarypist'oni 532,1ana outside ccndu-t: iiriss provided Referring', now particularly to..Egures. '721.` and 8a','itf.willjbe seen thatacombinationcontrol valveunit. and' auxiliary piston unit.. are mounted on the rear end of' thepiston rodQS, asindicated -generally ati-3. cylindricalsleeve. 14servesjzas a .housing for. the controhvaly'e. unit. 15, andas` acylinder. wallfor., the` auxiliary piston. 16.' .located in the reanportion-V thereof.. A frontp1ug- 1.1 seryes, to .connect-. the combinedunit 'l3 with -the histori-V. rod ;id- The` rearend1- ofthe.-cy-linder-v 14 is closed by. a Z pingi- 1-8.. from. thecircumferenee. of which .the threetie rods Vfilii..project and-connectWith-.tharear duet g-rinpingliunitla. ll'achtoif`` the timdsga isprovided-with.albaiifu Ozi-the. from; end.. thereof which fgta. in. asocket. provided-5 for in..the.uli1sfl8 1 z .The-;plusy 1.8 isalsoproivided. with-three. equisnacedopeninggs` il;throughV which:- thzree.equisnaoed. extensionsfvll--ofsthefniston 16 extend;The-.connectinggrods-Ailareeach: provided: with a hallonlthe;frontlendltheneofpwhich fitsfin a socket provided-therefon onthe,- rearr-end of each extension 81, as shown. Inordei'hormallyg-tohias the-auxiliarypiston 'I S-towardsfits foriivardf.Lposition-.adiacentc the control valve, unit 151 ccmprese sion' ''spring`8.3.' are. provided f-.on'z-.each :ofLp the .prof jee-tions 8.-iimbetween manna-18 andzthe piston Both-:the-plug ;TB-;andthe;.pistcrr.1ifareprovided With centralzoneningssforaccommodatingarztubu'- lerz:` section` 84 whichtransmitsf-'compressedz air from the'flexiblezacenneotion;411Y into; the.: twozway wntrOl-r valvezzuniti liThersectiozn` M contneeted` with the fiexible connection H? bymeiimsiofv an adapter Referring' to-Figures; 6; 7a.and 8a, iti-will beseen'that. two-way controlf valvel units-f 15V`` com` prisesa blockBlivprovided with-a centralzonening in whichi's; disposed: arotat'able;cylindrical; valve memberl: The block. 88.'hasanaupper exhaust port-.8dand a lower exhaust port' 90. The block 86 is provided at its-l frontendi with' a. port.` 9.| whichcommunicates with the ,upper passagewaylllfin .the pistonrod. 56,,and-.alower.portzllji which communicates.with the; lower' passagewayf' 'M3 in the piston rod 56. The portalso-communicates with a` passageway 9-3'r (Figurea) having.: a. shortVertical arm; and az longer' horizontal arml: which is. designated: at96- and' which opens into: the cylindrical space in front of theauxiliary-'piston 16-.

Referringv particularly to Figuresi and 6, .itfwill be'seen thatcentralhubs SiS-'and 9.6.-project: from opposite sides of' the.|cylindricalvalve.: member 87: and extend throughopeningsilzi-rovided:there-1 for' in thexside members91-whichaaresecured1to the valve-block 36-80 as. to retainthevalve-mamiher` 8.='l-in=place therein.` An LL-shapediarmhas the endA ofits Vertical. legV fitted'. over; andi pinned to the projecting-hub 95While-its--horizontalileg extenfls underthe Valve; block. dB.: and;carries'- a downwardly projecti-ng: pin lfl which extends' throughalong-itudi-nal, slot for-med in'` the; bot:- tom of' the cylinder 1.4;

In order to impart; a snap action-.to-:the-:valve member 811m moving.fi'om'onecontrol positiomto the other,v an v overecenter device: is=proyided'. on' that side of the valve-:block 'Bali-from .whichztheV hub96 projects. The over-center arrangementzisain the form of acrank1|.pinned.to-the,-hub.fi'and carrying a pin l'on the` outerenditheieofz. A tenson' spring.. m3- is' fastened over the: pin.: m2 atoneV end and the, other' end; of' the.. spring: 103 isfastened-toa-stationary pin' I 0,4 projectingzfnom thesidezinemberi 9.1:It will; be` anparent fromv Figure-S that When thev pin IW.: is moved'eitherto theL left. or right; of? the.v true. verticaif position; thespring; |03 actsV to-isnapfthefpin and-.the-;cylindrical' valve member-8'1': connected-f therewit'h to .their alternate positicm's;` o

The pin [00;and thereby thezcontrol'valve 15;. isactuated. bythe fi-atguide, strip. I'extendin'g along the -bottoin of the master,cylinder-15.1: and projeeting rearwardly therefrom. This'- guide strip`iii-5 is provided with along-.1 slot: 106i. in'lthe projecting` portionthereof'` through: which. slot therpin: IIll);extends'-;`` The. pinlllris-movedircm one. position to the; other` by: engagements: alter;nately with; the front.. and; near end: of the slot 106;

The. rel'ative movementbetweenthe master 'cy1f-. inder'unit' 51 of the;pneumatc'jmoton M'fanditho combi-nation'zunitf 1-3 sunnor-tedion thefreezend of thez pistorrrod;A 56sis.V guidedby. means of the; twocquispaced guide` strips; Ii'fli' (Figure-lfi` in come binaticn withstripv m5;` TheseV gnideistrips: HH may-y correspond' toguide; strip; I05 and: are'zequispaced' therefrom an` ang-mar; distanceaof 1209; as.showninFigure 2.. Each one-:of the-guide: strips l01'l is; also:provided. with:- a lengitudina'l' slot.: m8 in theprojecting portionthereof; andthcseslots engage rivets Mili- (Figure-` 1); providedion.the

cylinder 'M enelosing theacomhinationVV unitfl'; The detailed operationof thcarodd-ingz mechas nism"Hlfisasiollows:

' Referring'to iEigure '-8a` and* 8'b1-ofthes. drawings. the:twomxzay`control -xvalve' 11511118 showminone of its, twoalternate position.In--the' position-1 shown 'lv in Figure 8a, the pin is shown inengagement with the rear end of the slot IOG in the guide strip I sothat the pin Ifl i's moved to its forward position thereby bringing thevalve member' 81 into position to connect the port SI with the air inletconnection 84 while connecting the port 92 with the exhaust port 90. Inthis condition of. the valve member 81, air pressure is transmittedthrough the upper passageway in the'piston rod 56 and is applied to therear of the'double-acting piston 53 and through the passageway 66 issimultaneously applied to the rear of the auxiliary piston 58. Thepressure spaces in front of the double-actingpiston 53 and in front ofVthe auxiliary piston 'IB are exhausted through the port 92 and exhaustport390;

The air pressure applied to the auxiliary -piston 58 -forces itlforwardagainst the force-of the Springs 62, and causes the shoes 23 of thefront duct gripping unit I2 to be distended into duct grippingrelationship, as shown in Figure 8b, thereby preventing the cylinder 52from moving. At the same time, the pressure applied to the rear of thedouble-acting piston 53 causes this to move forward in the cylinder 52thereby advancing the rear duct gripping unit I3 (which is now in itscontracted condition) carrying forward With it the air hose I5. Theforward movement of the double-acting piston 53 continues until the pinIIJII is engaged by the front'end of the slot |06 as 'shown in Figure7a, whereupon, the over-center device causes the pin IDG to snap to itsrearward position thereby changing the position of the cylindrical valvemember 81 to that shown in -1" Figure 7a.

When the valve member 81 is in its position shown in Figure 7a, the port9| is interconnected with the exhau'st port 83 thereby relievingV thepressure applied to the rear of the double-acting cylinder 53 and to therear of the auXiliary piston 58. Thereupon the compression Springs 62cause the auxiliary piston 58 to move to the rear thereby contractingthe duct gripping unit I2. At the same time, the port 92 isinterconnected with the air inlet connection 84 whereby compressed airis transmitted through the lower passageway 'II in the piston rod 56 andis applied to the front side of the double-acting piston 53 which is nowin the position shown in Figure 7b. Also compresse'd airfrom the port 92is communicated to the passageway 93--9 into the pressure space in frontof the auxiliary piston 16 thereby causing it to be forced to the rear.Rearward action on the piston 16 serves to distend the conduit grippingshoes 36 of the rear duct gripping unit I3 as shown in Figure 7a. Sincethe double-acting piston 53 is held stationary by the rear of conduitgripping unit I3, the air pressure applied in front of the double-actingpiston 53 causes the cylinder 52 to be advanced thereby carrying forwardwith it the front conduit gripping unit |2 which is in its contractedposition.

The cycle of operation described above in connection with Figures 8a and8b' and Figures 7a and '7b is repeated as long as the duct roddingmechanism VII) is in operation, thereby causing the front and rear ductgripping units I2 and I3, respectively, to alternately advance throughthe duct I I so as to rapidly advance the duct rodding more firmly. toengage with the conduit with an increased gripping force which isdirectly proportional to the increasein pull or backward force. It willalso be seen that the front and rear duet gripping units |2 and |3 arefree to shift independentlyof each other and independently of the motorunit Ill thereby allowing a limited amount of independent movement.However, this movement is suflcient to allow the duct rodding mechanismIll to negotiate bends or curves in the ducts I I and also to pass oversmall obstacles therein.

After the duct rodding machine Ill has traversed a duct or conduit, acable or conductor may be attached to the air hose I5 at either end ofthe duct and then drawn therethrough. If for any. reason it is desiredto withdraw the machine Ill before it has completely passed through aduct, the air ,pressure on the hose |5 is shut offA and released therebyallowing both duct gripping units I2 and I3 to be contracted andpermitting the machine IO to be easily withdrawn by means of the airhose I5.

It will be Vapparent to those skilled in the art that certain changesand modifications may be made in the foregoing construction withoutdeparting from the spirit and scope of the invention. Accordingly, allmatter described above or shown in the accompanying drawings is intendedas illustrative and not in a limiting Sense.

Having fully described the invention, what we claim as new is:

1. A duct rodding machine comprising, in combination, a normallycontracted front duct gripping unit, a normally contracted rear ductgripping unit, 'and a fiuid pressure operated motor unit operativelyinterconnected between said front and rear duct gripping unit, saidmotor unit being cyclically 'operable to distend said rear duct grippingunit into duct gripping engagement and advance said front duct grippingunit in its contracted condition and thereafter cyclically operabletodistend said front duct gripping unit into duct gripping engagement andadvance said rear duct gripping unit in its contracted condition.

2. A duct rodding machine comprising, in combination, a normallycontracted front duct gripping unit, a normally contracted rear ductgripping unit, and a fluid pressure operated motor unit non-rigidlysupported by and between said duct gripping units and operativelyinterconnectedtherewith, the non-rigid support connectio n between saidmotor unit and said duct gripping-units permitting the latter to shiftindependently of each other and with respect to the longitudinalaxis'of'said motor' unit,and said motor unit being cyclically operableto distend said rear duct `grip'ping unit into duct gripping engagementand advance said front duct gripping unit in its contracted conditionand thereafter cyclically operable to distend said front duct grippingunit into duct gripping engagement and advance said rear duct grippingunit in its contracted condition. 3. A duct rodding machine comprising,in combination, a front duct gripping unit having a set of retractablymounted duct gripping members, spring means operatively connected withsaid gripping members so as normally to bias them in a contractedposition, a fluid pressure operated' power unit operativelyinterconnected with saidduct gripping members so as to distend thesame-into duct gripping engagement, a rear duct gripping unit vhaving aset of retractably mounted duct, gripping members, spring meansoperatively connected With said second` set of duct gripping jmembers soas normally to bias them in a contracted position; a fluid pressureoperated power unit operatively interconnected'with said second set ofductigrippingv members so as to distend the same into duct g'rippingengagement, ,a master cylinder unit comprising a` pressure lcylinderdisposed between said first and second fluid pressure operated powerunits and a double-acting piston in said cylinder, meansinterconnectingrsaid pressure cylinder with voneof said fiuid pressureoperated units for forward movement therewith, means interconnectingsaid double-acting piston with the other of said fiuid pressure operatedunits for forward movement therewith, and a two-Way lpressure controlvalve operatively interconnected with said 'first' and second fluidpressure operated units and with-said master rcylinder unit, saidcontrol valve in one position admitting fluid pressure to one of saidfluid pressure operated units and to one side of said double-actingpiston and in the second position admitting fluid pressure' to the otherof said fluidpressure operated units and to the'opposite side of saiddouble-acting piston, whereby in cyclic operationsaid rear duct grippingunit is distended into duct gripping engageinent While said front ductgripping unit in coutracted condition is advanced and thereafter saidfront duct gripping unit is distended into duct gripping iengagementwhile said rear duct gripping unit in contracted condition is advanced.

4. A duct gripping unit for a duct rodding` machine of the classdescribed comprising, in combination, a hub member, a plurality of ductgripping shoes, and a pair of substantially parallel support links ofsubstantially equal length for each of said shoes with each pair of saidlinks being pivotally connected at their outer endsadjacent to the frontand rear portions respectively of one ofsaid shoesand being pivotallyconnected to said hub and Operating rods pivotally connected to a linkof each pair.

5. A fluid pressure operated motor ,unit for combination with a duct'rodding machine having front and rear duct gripping units normallycontracted, and distendible into duct gripping engagement, said motorunit comprising, in combination, an elongated pressure cylinder,`aidouble actingpiston in said cylinder, a hollow partitioned piston rodconnected at one end to said piston and projecting at its opposite end..from oneend' of said cylinder, a two-way control Valve unit and acombination auxiliary piston and cylinder unit mounted on the outer endof said piston rod, a second combination auxiliary piston and cylinderunit mounted on the end of said pressure cylinder opposite that fromwhich said piston rod projects, a fiuid pressure transm'itting conduitinterconnecting the compression Chamber of said second combinationpiston and cylinder unit with said pressure cylinder adjacent said endthereof from which said piston rod projects, and a snap-acting Operatingmechanism for turning said control valve having one Operating elementcarried on the movable part of said Valve and a cooperating Operatingelementcarried on said pressure cylinder and connected in lost-motionrelationship with said first Operating element, the auxiliary pistons ofsaid combination piston and cylinder units being adapted to beoperatively interconnected with the adjacent duct gripping units, and incyclic operation said two-way control valve in one conditiontransmitting fluid pressure to one side of said double-acting piston andto the com-' to the other combination auxiliary piston and cylinderunit.

6. A duct rodding machine comprising, in

combination, front and rear duct gripping lunits and'afluid pressureoperated motor unit interconnected between said duct gripping units,each of said gripping units comprising, a hub member,

la plurality of duct .gripping shoes and a pair of 'support links foreach of said shoes with each pairjof said links' beingpivotallyconnected at their outer ends `adjacent to the front and rearportions respectivelyof one of said shoes and being `pivota1ly connectedto said hub with one link in each of said pairs thereof being in theform of a bell crank with its pivotal connection to said hub being atthe fulcrum thereof, said motor .unit comprising an ,elongated pressurecylinder having one of the vend walls thereof located inwardly of theadjacent end of the cylinder, a double-acting piston in said cylinder, ahollow partitioned piston rod secured at one end to said double-actingpiston and projecting at its opposite end from said end of said pressurecylinder wherein said end wall is inwardly disposed, a two-way controlvalve unit and a combination auxiliary piston and cylinder unit mountedon said projecting end of said piston rod with'said two-way control`valve unit being disposed inwardly of said combination auxiliary pistonand cylinder unit, a piston disposed in said end of said pressurecylinderV wherein said end wall is inwardly disposed anda wall'closingthe outer end of this end of said pressure cylinder so as to formtherein a second combination auxiliary piston and cylinder unit, a fluidpressure transmitting conduit interconnecting the compression chamber ofsaid second combination auxiliary piston and cylinder unit with saidpressure cylinder a'djacent the opposite end thereof, and an overcenterOperating mechanism for said control valve having one operating'elementcarried on the movable part of` said valve and a cooperating operatingelement carried lon said pressure cylinder and interconnected inlost-motion relationship with said fir'st (valve Operating elementwhereby said control valve is snap operated to one control conditionwhen said double-acting piston is adjacent one end wall of said pressurecylinder and is snap operated to its other control condition when saiddouble-acting piston is adjacent the opposite end wall of said pressurecylinder, connecting rods operatively interconnecting the auxiliarypiston of each of said combination auxiliary piston and cylinder unitswith said bell crank links on the adjacent duct gripping unit wherebymovement of said auxiliary pistons serves to distend the respective ductgripping units into duct gripping engagement, and a plurality of tierods interconnecting the hub member of each of said duct gripping unitswith the cylinder of the adjacent one of said combination auxiliarypiston and cylinder units with the opposite ends of said plurality oftie rods being fastened in ball and socket joints whereby each of saidduct gripping units may move with respect to its longitudinal axisindependently of said intermediate motor unit,

and in cyclic operation said two-way controll valve in one condition'transmitting fiuid Vpressure to one. side of said doubl'e-acting.piston and. .to

the combination auxiliary piston .and cylinder unit on the opposite sidethereof. until saiddoubleacting piston is located 'in .the opposite .endof said pressure cylinder Whereupon saidl. valve opwhereby each headmoves 'with .its .connected motor part, and fluid pressure operatedmeans for alternately actuating each set Vof vduet gripping jaws, saidlatter means 'being `controll'edby said 'automatic valve.

8. The combination of claim .7, wherein'said fiuid pressurel operatedjaw actuating means-.comprise' a pairv of motor members 'each carried bythe adjacent motor part,Y and Operating .rods

fiexibly connecting said motor members and said jaws.

` 9'. A laterally fiexible fluid pressure motor actuated duct roddingmachine, comprising an automatic fiuid Vpressure operated reciprocatingmotor having two 'main moving parts, an automatic control valve, and apair of duct gripping units having automatically retractable andexpansible jawsV connected toV said parts respectively, at Vleast one ofsaid 'units c'ompris'ing a head, a lplurality of links 'pivoted' Aon the.head and 'connected toV the corresponding jaws, a radius rod fiexiblyconnecting the head' to the corresponding motor parts, a fiuid pressureoperated member carried by the sai'd'corresponding motor part, and-controlled by said Iauton'i'atic valve, and a connecting rod fiexiblyconnecting said member with said link.

10'. In adevice of the cIass-described,the'combination of a front duetgripping unitand alrear duct gripping vunit `'both having -movablegripping jaws, av main double acting -reciprocatingi'pressure 'actuatedmotor disposed between Vand connected to *said units, comprising adouble lended 12 cylinder and a piston therein ladapted to bereciprocated in. said cylinder, an 'automaticallyactuatedpressure-.fluid control valve for alternately admitting andexhausting pressure fiuid -from.each end of.v the cylinder,.a pair ofauxiliary .single acting pressureactuated motors each vhav- .ing acylinder communicating atall times with Vsponding .main ,motor .partsand laterally flexible 'connecting rods between the auxiliary motors andthegripping jaws of the. unit.

'12. In a device of the Vclass described, a .main reciprocatng, doubleacting fiuid pressure actuated motor .having .an automatic valve, andcomprising4 two parts automatically movable un- `der fiuid pressurealternately towa'rd and laway from each other under the controlzof saidvalve, a front 'duct gripping unit connected toone motor part, a. rearduet .gripping unit connected to the other motor part, veach .unitcomprising a head and pivoted jaws, a radius .rod fiexiblyconnecting thehead 'to the `correspionding :motor part, each of said'v motor partscarrying a jaw actuating fiuid pressure .operatedmotonand there being afiexible operating connection from said jaw actu'ating'fluidpressure.operated motor to each of said pivoted jaws, saidjaw actuating motorsoperating alternately .withsuccessive motons .of the 4mainmotor partswhereby the device is progressively advanced 'by alternate forward.movementof'the .main motor .partsand connected duet gripping units.

CRONJE JASPER.. GEORGE T. HAWK.

REFERENCES 'oi'rlp The following .references are of record in 'the fileof this patent:

. STATES PATENTS

